We plan to characterize the chromosomal arrangements of a coordinately and sequentially expressed multigene family because we believe such structural information is necessary to an understanding of the mechanisms of sequential gene control which underlie both normal eukaryotic development and abnormal gene expression during oncogenesis. The genes we are studying encode the chorion (eggshell) proteins of the silkmoths Antheraea polyphemus. Fragments of chromosomal DNA containing sequences encoding these genes have been isolated using recombinant DNA technology. We plan to use these clones to ask whether the chorion structural genes are closely linked. If close linkage exists, we will want to know the nature of the spacer sequences and the relationship of the linked genes to each other; i.e., are the linked genes related structurally, or are they genes which are expressed coordinately. We will also use these cloned fragments to study the nature of the sequences adjacent to the structural genes, since such sequences may contain cis-acting regulatory elements. We will compare sequences adjacent to coordinately expressed genes to those adjacent to sequentially expressed genes. We will also examined the sequences encoding the structural genes to see if these genes contain "intervening sequences" similar to those found in other eukaruotic genes. If present, these sequences will be compared in chorion genes which are homologous as well as in genes which are expressed coordinately and sequentially. These studies will utilize restriction enzyme analysis, DNA sequencing, DNA:DNA and DNA:RNA hybridization and electron microscopy.